class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) 
    {
        unordered_map<int,int> hash;
        for(int i=0;i<nums.size();i++)
        {
            int x=target-nums[i];
            if(hash.count(x))
            {
                return {i,hash[x]};
            }
            hash[nums[i]]=i;
        }
        return {};
    }
};